is the land public or private property?
Sounds public from your original post - because if it was private, this could all be resolved by discussing it w the landowner.
If it is public, there's really not much you can do other than make room for him - because unfortunately, he has just as much right to hunt there as you do. As for being so close to your stand, MAYBE you can talk him into moving into one of the corners of the lot, but frankly he doesnt have to. Stinks that someone found your spot, but on public land, they have a right to be there too.
If you just HAVE to get him out of there, you should be friendly but secretly use some reverse ol school hunting psychology on him - maybe by making up a story like "you, your kids, and your nephews are hunting in there too and they are just learning the ropes, so feel free to offer them any advice as the season goes along", after you lock a big two man stand to a tree about 10 yards from his tree and make it look like everyone and their brother is hunting in there, I bet you wont see him coming back